Drive Maintenance

The following section provides information about status indicators for logical and hard disk drives, and the results of a hard disk drive failure.  It also contains procedures for replacing defunct drives and for redefining the space in an array by replacing logical drives.

Subtopics:
o Obtaining Drive Status
o Results of a Hard Disk Drive Failure
o Logical and Hard Disk Drive Status Indications
o Replacing a Faulty Drive
o Redefining Space in an Array

Obtaining Drive Status
To see the ID, capacity, and other information about each of the hard disk drives attached to the RAID adapter:

 1. Start the RAID configuration program by inserting the IBM RAID controller diskette into the primary drive and turning on the system.  If the system already is on, press Ctrl+Alt+Del.
 2. Select Drive information.
 3. Use the Up Arrow or Down Arrow to highlight each of the drives shown in the Bay/Array selection list.  As a drive is highlighted, the information for that drive is shown at the bottom of the screen.
 4. Press Esc to return to the Main Menu.
    Note:  Status of the hard disk drive determines the status of the logical drives in the array in which the hard disk is grouped.

Subtopics:
o Bay/Array Selection List
o Blank Status

Bay/Array Selection List
Status
Meaning
CDR
CD-ROM drive installed.
DDD
Defunct.  The drive is an online or hot-spare drivethat does not respond to commands.  (If a RDY drive is defunct or powered down it shows an empty bay (a blank status) not a DDD status).
FMT
Format.  The drive is being reformatted.
HSP
Hot spare.  The drive will replace a similar drive that becomes defunct in real time.  At that time  its status changes to ONL  and its array association is displayed.
OFL
Offline.  The drive is a good drive that has replaced a defunct drive in a RAID level 1 or level 5 array.  It is associated with an array but does not contain any valid data.  The drive state remains OFL during the rebuild phase.
ONL
Online.  The drive is part of an array.  If this drive fails, logical drives defined in the array in which this drive is grouped will have a status of offline (if the logical drive is assigned RAID level 0 with a good status) or Critical (if the logical drive is assigned RAID level 1 or level 5 with a good status).
RDY
Ready.  The drive is recognized by the adapter and is available for definition.
TAP
Tape drive installed.
UFM
Unformatted.  The drive requires a low-level format before it can be used in an array.

Blank Status
Any of the following circumstances can cause the status area to be blank:
o No hard disk drive is installed in that bay.
o The bay contains a hard disk drive, but the drive is not inserted correctly.
o An array was deleted and a defunct drive is still in the bay.
o A new drive was installed and the configuration program has not been restarted.  (Status will change to RDY when RAID configuration program is restarted.)

Results of a Hard Disk Drive Failure
There can be several possible results from a drive failure.

Scenario 1:
o Only one hard disk drive fails.
o A hot-spare drive is defined that is the same or greater size than the failed drive.
o The logical drives in the array are assigned RAID level 1, level 5, or a combination of these two levels.
Then the hot spare will take over immediately.  Data for logical drives assigned RAID levels 1 and 5 is maintained; however, system performance will be reduced.  Hot-spare drive capability does not apply to logical drives assigned RAID level 0.

Scenario 2:
o Only one hard disk drive fails.
o A hot-spare drive is not defined.
o The logical drives in the array are assigned RAID levels 1, 5, or a combination of these two levels.
Then no data will be lost, but the system will operate at reduced performance until the defunct drive is replaced and rebuilt.

Scenario 3:
If more than one drive fails, all data is lost.  Therefore, it is important that you replace and rebuild a defunct drive as soon as possible.

Logical and Hard Disk Drive Status Indications
The status of the hard disk drive determines the status of the logical drives in the array in which the hard disk is grouped.

o A single hard disk drive failure (indicated by a DDD status in the Bay/Array selection list) causes logical drives in that array that are assigned levels 1 and 5 to have a Critical status.  Data remains in logical drives with a Critical status, but you must replace the one defunct hard disk drive promptly, because if two hard disk drives were to fail, all of the data in the array would be lost.
  After you install a new hard disk drive, the Replace process changes the drive status from DDD to OFL if there is a Critical logical drive.  After the Rebuild process, the hard disk drive status changes from OFL to ONL.

o A single or multiple hard disk drive failure causes logical drives in that array that are assigned level 0 to have an offline status.  Data in logical drives with an offline   status is lost.  However, with a multiple disk drive failure, when the defunct drives are part of the same array, logical drives in that array will have an offline status.  This means that data is lost in all the logical drives in that array, regardless of which  RAID level is assigned.

Replacing a Faulty Drive
The hard disk drive indicator light will blink when the drive has failed and needs to be replaced (DDD state only).  See Removing a Drive from Bank C, D, or E to locate the faulty hard disk drive.

To replace a faulty drive:
 1. Start the RAID configuration program by inserting the IBM RAID controller diskette into the primary drive and turning on the system.  If the system already is on, press Ctrl+Alt+Del.
    If the drive failed while the system was powered down, a screen appears the next time the system is powered on showing you which drive is defunct.
 2. If the drive is not damaged (for example, it is not inserted correctly):
    a. Turn off the system.
    b. Correct the problem.
    c. Remove the diskette or ServerGuide CD from the drive.
    d. Restart the system.
 3. If the drive is defunct:
    a. Press Y (Yes) to reconfigure the system.
    b. Press Ctrl+Alt+Del when instructed to restart the system.  The Main Menu appears.
    c. Select Rebuild device.  At this point, the drive status shows DDD.
       Warning: Removing the wrong hard disk drive can cause loss of all data in the array.
    d. Replace the defunct drive.  Refer to Removing a Drive from Bank C, D, or E.
    e. After you have replaced the drive, press Enter.  The system will reconfigure to include the drive, and the drive's status will change to OFL.
    f. Allow the system to complete the configuration (the screen displays a completion message); then select Rebuild drive.
    g. Use the Up Arrow or Down Arrow to highlight the OFL (offline) drive you want to rebuild; then press Enter.  (The progress of the rebuilding process appears on the screen.)
    h. When the rebuilding process completes, press Esc to return to Main Menu.  The new configuration is saved automatically.
    i. Backup the new configuration (see Backing Up Your Disk-Array Configuration).
    j. Select Exit to end the RAID configuration program.
    k. Remove the diskette and press Ctrl+Alt+Del to restart the system.

Redefining Space in an Array
You can redefine space in a disk array in a number of ways.  For example, you can combine a number of small logical drives to create a larger one or you can redefine the existing logical drive into several smaller drives. Also, you can install additional hard disk drives to create a larger logical drive than was possible with the existing storage capacity.
   One method to redefine space in an array is to change the RAID level assigned to a logical drive.  For example, if you assigned RAID level 1 to a logical drive and then decided you needed the capacity offered with RAID level 5, you can use this procedure to replace the existing logical drive with a logical drive assigned the new RAID level.
   To redefine the space in a disk array, first you must delete the array.  The last disk array defined must be the first deleted.
Warning: In all cases, when you delete an array, all the data and programs in the array are lost.
   If you have data and programs that you want to save, they must be backed up and then restored.  It is suggested you use a high-speed backup device, such as a tape drive. To redefine the space in an array:

 1. Back up all data and programs in the array.
 2. If needed, install additional hard disk drives. Refer to the User's Reference for information about selecting drive sizes.
 3. Insert the IBM RAID controller diskette; then press Ctrl+Alt+Del to start the RAID configuration program.
 4. Delete the existing array:
    a. Select Create/delete array from the Main Menu.  The Create/Delete Array menu will disappear.
    b. Select Delete disk array.  The cursor will be active in the Bay/Array list.
    c. Review the Logical Drive List Date Created column; then press the Up Arrow or Down Arrow to highlight the most recently defined array. Note:  You must delete disk arrays in descending order; the last one created must be the first one deleted.
    d. Press Del.  The Confirm pop-up window appears. Warning: All data in the array will be lost during this procedure.  Be sure to back up all data and programs you want to save.
   e. If you do not want to delete the array, select No.  To delete the array select, Yes.  Note:  To use the hard disks from the existing array when creating a new array, you must confirm the deletion of the existing array.  After you make your selection, the Confirm pop-up window will disappear, and the cursor will be active in the menu.
 5. If you want a drive defined as a hot spare, refer to Defining a Hot-Spare Drive for step-by-step instructions.
 6. Create a new disk array and define logical drives. See Creating a Disk Array for instructions on creating a disk array and defining logical drives.
 7. After you have established the new array and logical drive or drives, select Initialize/synchronize array from the Main Menu; then select Initialize logical drive to prepare the drives in the array to receive data.  This sets the drive to a predetermined state.  Any data existing in the drive is overwritten with zeros, and corresponding parity is initialized to the proper value.
 8. Insert a 3.5-inch formatted diskette in the primary drive, select Advanced functions from the Main Menu; then select Backup config. to diskette.  Follow the instructions on the screen.
 9. Exit the RAID configuration program by pressing Esc or selecting Exit while on the Main Menu.  A pop-up window will appear asking you to confirm your action.
10. Reinstall your operating system and device drivers, then restore your data and programs.

Configuring the Disk-Array

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